1. Field of the invention
The present invention relates to a method of removing a photoresist layer on a semiconductor wafer, and more specifically, to a method of removing a photoresist layer on a semiconductor for a production of a small quantity.
2. Description of the Prior Art
In semiconductor manufacturing, a development process is performed to transfer the pattern of a photoresist layer onto a semiconductor wafer after the exposure process and the post exposure baking process. Normally the development process starts with pre-wetting the semiconductor wafer using DI water. A developer is then sprayed on the semiconductor wafer to perform a puddle development process. Finally, the photoresist layer is removed at the end of the development process.
The method of removing the photoresist layer on the semiconductor wafer starts with placing a batch of semiconductor wafers into a dry strip chamber. An ashing process, using a plasma comprising oxygen or ozone, is performed to remove the photoresist layer on each semiconductor wafer. There are normally 24 pieces of the semiconductor wafer per batch. Thus the duration of the ashing process is approximately 30 minutes per batch.
Since the photoresist layer comprises polymeric resins, photo-sensitizers and organic solvents, there are often residual polymers, organic components and particles on the surface of the semiconductor wafer after the ashing process. Thus the batch of the semiconductor wafers is then placed into a first rinse tank. A first rinse process, using a solution of sulfuric acid (H2SO4) and hydrogen peroxide (H2O2) as a first rinse solution and having a duration of 15 minutes per batch, is performed to remove polymers and organic components on each semiconductor wafer.
The batch of semiconductor wafers is then placed into a second rinse tank. A second rinse process, using DI water as a second rinse solution and having a duration of 10 minutes per batch, is performed to remove the residual first rinse solution on each semiconductor wafer.
Then, the batch of semiconductor wafers is placed into a third rinse tank. A third rinse process, using a standard cleaning solution (SC-1) as a third rinse solution and having a duration of 10 minutes per batch, is performed to remove organic components and particles on each semiconductor wafer.
The batch of the semiconductor wafers is then placed into a fourth rinse tank. A fourth rinse process, using DI water as a fourth rinse solution and having an approximate duration of 10 minutes per batch, is performed to remove the acid in the residual third rinse solutions on each semiconductor wafer.
Finally, the batch of semiconductor wafers is spun dry in a horizontal rotational plane at a rate ranging from 2000 to 2500 rpm for approximately 15 seconds per piece, so the duration of spinning dry the batch of the semiconductor wafers is approximately 6 minutes. Consequently, the method of removing the photoresist layer on the surface of each semiconductor wafer, including the ashing process, the first, second and third rinse processes, the spin-dry process and procedures of moving the batch of the semiconductors from tank to tank, has an approximate duration of 2 hours.
However, the method of removing a photoresist layer from a semiconductor wafer according to the prior art is merely efficient in batch production. In production with a small quantity, such as a pilot-run production, the duration of removing the photoresist layer from the semiconductor wafer is still approximately 2 hours even with a quantity of only single or a few semiconductor wafers. The manufacturing cost is thus increased by this inefficient production.
It is therefore a primary object of the present invention to provide a method of removing a photoresist layer from a semiconductor wafer in a production with a small quantity so as to improve the production efficiency.
According to the claimed invention, a semiconductor wafer is placed into a dry strip chamber. A dry stripping process is performed to remove a photoresist layer on the semiconductor wafer. The semiconductor wafer is then placed on a rotator of a wet clean chamber, comprising multiple nozzles, and rotated horizontally. A cleaning process, comprising a first, second, third and fourth cleaning processes and having a total duration of 140 seconds, is then performed. Finally, the semiconductor wafer is spun dry for approximately 20 seconds at the end of the method.
It is an advantage of the present invention against the prior art that the photoresist layer is removed by spraying the cleaning solutions onto the surface of the rotating semiconductor wafer instead of by rinsing the semiconductor wafer according to the prior art. In a production with a small quantity, such as a pilot-run production with a quantity of only single or few semiconductor wafers, the duration of removing the photoresist layer on the semiconductor wafer is only less than 4 minutes for each piece. Thus the production efficiency is significantly improved, and the production cost is consequently reduced.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the multiple figures and drawings.